Explosively actuated cutter

ABSTRACT

Apparatus for cutting a hard elongate workpiece having a slideable cutter piston positioned within a cylindrical housing, such piston being actuated by an explosive charge located within the housing, which upon actuation will thrust the piston with great force against an appropriately positioned workpiece thereby cutting the workpiece. A series of gas-sealing elements within the device prevent the discharge of explosive resulting gas and prevent fluid entry.

United States Patent Lieberman 1 Feb. 22, 1972 [54] EXPLOSIVELY ACTUATED CUTTER [72] Inventor: Morris S. Lieberman, Silver Spring. Md.

[73] Assignee: The United States of America as represented by the Secretary of the Navy 22 Filed: Apr. n, 1970 211 AppLNo: 29,574

3,246,396 4/1966 Temple ..30/DIG. 4 3,353,267 11/1967 Temple ..3U/18O FOREIGN PATENTS OR APPLICATIONS 919,940 11/1954 Germany HBO/DIG. 4

Primary ExaminerAndrew R. Juhasz Assistant Examiner-Michael Koczo, Jr. Attorney-R. S. Sciascia and J. A. Cooke [57} ABSTRACT Apparatus for cutting a hard elongate workpiece having a slideabie cutter piston positioned within a cylindrical housing, such piston being actuated by an explosive charge located within the housing, which upon actuation will thrust the piston with great force against an appropriately positioned workpiece thereby cutting the workpiece. A series of gas-sealing elements within the device prevent the discharge of explosive resulting gas and prevent fluid entry.

1 Claim, 3 Drawing Figures PATENTEUFEBZZ 1972 3.643.329

SHEET 2 BF 2 FIG. 3

BACKGROUND OF THE INVENTION This invention relates generally to cutting tools and more particularly to an explosively actuated cutter for hard elongate articles such as pipe, chain or the like.

in cutting hard objects. such as pipe or chain, a great amount of force must be exerted on the cutting member to enable it to sever the workpiece. Explosively actuated cutters wherein cutting members are driven across work-receiving openings transverse to the path of the cutting member by expanding gases resulting from an explosion are being used for a wide variety of work functions such as cutting of conduit, bar stock, heavy cable, riveting and the punching of holes. Present day cutters tend to be large, heavy, bulky single-shot devices which are relatively complicated to operate and expensive to manufacture. Furthermore, many prior art explosively acmated devices llclt sufficient sealing apparatus and it is not uncommon to find a tool of this ltind rendered inoperable clue to the shipment and/or storage of such tool in a moist environment. Very often this occurrence necessitates a time-consuming reconditioning operation which results in lower productivity. It will be recognized that devices of this kind are not suited for underwater applications.

' A further significant problem encountered in the use of prior art tools of this nature is the extremely high level of noise produced by the actuation of the explosive charge. More particularly, it is a frequent practice to employ explosively actuated cutters in relatively confined areas such as the hold of a ship or cargo compartment of an airplane. The nature of these surroundings is such as to magnify the sound of the blast to a deafening level. This noise problem is acute even when used in unconfined spaces being both annoying to all those within an audible range and hazardous to the operator after repeated use. Additionally, clandestine applications of cutters require a relatively silently operating cutter which is unavailable in the prior art.

SUMMARY OF THE IN VENTlON Accordingly, one object of this invention is to provide a new and improved explosively actuated cutter.

Another object of the instant invention is to provide a new and improved small. light, compact explosively actuated cutter.

Still another object of the present invention is to provide a new and improved small, light explosively actuated cutter which is operable when immersed in a fluid environment.

A further object of this invention is to provide a new and improved explosively actuated relatively silent cutter for hard objects.

A still further object of the instant invention is to provide a cutter particularly suitable for severing chains.

Briefly, these and other objects are obtained by an explosively actuated cutter having a housing assembly embodying sealing devices for rendering the cutter both silent and waterproof.

BRIEF DESCRIPTION OF THE DRAWINGS A more complete appreciation of the invention and many of the attendant advantages thereof will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. I is a side view in full cross section of the explosively actuated chain cutter in the cocked position;

FIG. 2 is a front view of the cutter shown with the striker guide subassembly not attached with a chain positioned in the work-receiving recess thereof shown in phantom lines; and,

FIG. 3 is a side view ofthe striker guide subassembly shown in complete section.

2 DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, wherein like reference nu merals designate identical or corresponding parts throughout the views, and more particularly to FIG. 1 thereof. the explosively actuated cutter apparatus of the present invention as shown by general designation 10 consists essentially of a cutter housing assembly 12. a striker guide assembly 14 threadedly affixed to the upper extremity or breech end of cutter housing assembly. and a stop msembly l6 threadedly secured at the lower extremity or muzzle end of the cutter housing assembly 12. The cutter housing assembly l2 embodies a cutter housing 18 which consists of a substantially cylindrical member whose breech and muzzle ends are provided with threaded portions 21) and 22, respectively, a stepped portion above threaded portion 20 of lesser diameter than cutter housing 18 formed axially and integrally therewith and a slideable cutter piston 23 which will be more fully described hereinafter. Cutter housing [8 is provided at its upper end with a first axial bore 24 which cooperates with a second counterbore 26 ofgteater diameter than the axial bore 24 defining a shoulder 28. A third counterbore 30 is provided at the lower extremity of cutter housing 18 which opens into second counterbore 26 and has a greater diameter than the second counterbore 26. The point at which the third counte rbore 30 converges with the second counterbore 26 defines a beveled shoulder 32 which is contained by substantially the same plane as defined by the uppermost cross section of lower threaded end 22. Substantially adjacent to and above the up pcrrnost portion of the lower threaded end is positioned a work-receiving opening 34 formed in cutter housing 18. The work-receiving opening 34 may be defined by alternate linksupporting surfaces 36 and 38 (see FIG. 2) which form protrusion 60 which serves to separate links adjacent to the link to be cut and concave supporting surfaces 42 on which the chain link to be cut is positioned beneath the cutter piston 23 as will be discussed more fully hereinafter.

Cutter piston 23 consists ofa cylindrical member of height substantially equal to the distance between shoulder 28 and the work-rcceiving opening 3-4. Adjacent the upper end of the cutter piston 23 is situated an O-ring seal 44 positioned within a circumferentially extending groove 46. This seal is in constant mutual contact with the surface of counterbore 26 and the cutter piston 23 at all times thus effecting an airtight barrier between axial bore 24 and work-receiving opening 34. It should be noted that this seal is maintained even as cutter piston 23 slides within second counterhore 26.

inserted within first axial bore 14 is an explosive charge 48 which preferably consists ofa .22 caliber blank cartridge. A shallow counterbore 50 is provided to receive the rim 52 of charge 48 in order to provide a continuous top surface 54 on cutter housing l8.

A striker guide assembly 14 is threadedly affixed to the upper portion of the cutter housing assembly l2 whose main purposes are the initiation of explosive charge 48 and the provision of an effective seal to prevent the escape of the resulting gases. The striker guide assembly 14 includes a retainer 56 which houses a firing pin 58, a low density polyurethane disc 59 overlying the firing pin, a seal 60, a striker guide 62 and a series of O-rings suitable to seal the assembly which will be discussed hereinafter.

Retainer 56 is a substantially cylindrical shaped member in which a series of bores and communimting counterbores are formed on two offset axis. As more clearly shown in FIG. 3, a first bore 64 and a second internally threaded communicating counterbore 66 are formed on a first axis 68 which coincides with the axis of the cylindrical retainer. The threaded counterbore 66 is so formed to permit receivable threaded engage mom with the upper threaded end 20 of cutter housing 18 wherein stepped portion 25 communicates with first bore 64. It is seen that stepped portion 25 is provided with a groove 27 for reception of a second O-ring 29 which provides an airtight seal when in contact with retainer 56. it is to be noted that axis 68 coincides with the axis about which the cutter housing axial bores are formed. A second axis 70 radially offset from first axis 68 provides a centerline for a third bore 72 which opens into first bore 64 and further a fourth bore 74 which is of larger diameter than and axially communicates with the third bore. A partially internally threaded fifth bore 76 which is of larger diameter than and opens into the fourth bore 74 faces the upper end of retainer 56 and communicates with the upper surface thereof The firing pin 58 consists of upper and lower elongate portions 78 and 80, respectively, separated by a sealing portion including two flat circular discs 82 and 84 which define a circular groove 86 therebetween. The firing pin 58 is constructed such that the lower elongate portion 80 thereof is received in bore 72 while the sealing portion defined by discs 82 and 84 is contained in bore 74. A third O-ring 88 is seated in circular groove 86 whereby such O-ring is in constant sealing contact with the inner surface of the fourth bore 74 to prevent the escape of any gases which are produced upon the initiation of explosive charge 48.

A cylindrical externally threaded seal member 60 having an axially extending bore 92 of sufficient diameter to receive the upper elongate portion 78 of firing pin 58 is threadedly secured in fifth bore 76 thereby securing firing pin 58in place. Threaded seal 60 further enables the positioning of a fourth O- ring 94 between the bottom surface of threaded seal 60 and the top surface of sealing portion disc 82 and a fifth O-ring 96 in circumferentially extending groove 98 formed in the unthreaded portion of threaded seal 60 wherein the fifth O- ring is in constant sealing contact with the inner surface of fifth bore 76.

As more clearly shown in FIG 1. when properly assembled the bottommost surface of firing pin 58 is in contact with the edge of cartridge rim S2 and the upper extremity of the upper elongate portion 78 extends above the top surface of seal 60. Slideably contained on the outer surface of retainer 56 is striker guide 62 which when pushed down to its depressed position as shown in FIG. 3 communicates with the upper surface offiring pin 58 through the polyurethane disc 59 thereby driving the pin into engagement with charge 48 and igniting it. Striker guide 62 is provided with a plurality of air escape openings which permit the release of any air which may have been entrapped as the striker guide is depressed and which would have prevented the rather effortless firing of the device.

Retainer 56 is preferably coated with Teflon to facilitate any subsequent separation of the cutter housing 18 from the retainer and further to reduce any noise created by the rubbing of the retainer 56 and striker guide 62. A roll pin 104 is positioned adjacent the retainer within a cutout portion thereof, and cooperates with flattened retainer surface 105 and striker guide 62 thereby capturing the striker guide 62 to the retainer 56 while permitting the striker guide to be raised to a sufficient height so that it can be pushed down suddenly with a force sufficient to strike the firing pin 58 and fire the charge 48. Conventional safety apparatus is provided which includes a circumferentially extending safety pin groove 102 formed in retainer 56 below and substantially adjacent to the flattened retainer surface 105. When the striker guide 62 is in a low position [as in FIG. 3) the safety pin groove I02 cooperates with corresponding openings in the striker guide (not shown] and a safety pin III is inserted thereby preventing any relative movement between the retainer 56 and the striker guide 62.

Stop assembly l6 includes a substantially cylindrical stop member 110 and contained therein a steel washer 112, a lead slug H4 and a set screw 116 The stop H0 is provided with upper and lower internally threaded axial bores [18 and 120, respectively between which is formed a stepped cylindrical cavity 122 consisting of a first subcavity 124, a second subcaiity 126 formed above the first subcavity I24 and of a smaller diameter, and a third subcaviiy 128 positioned below the first subcavity and being of the least diameter. The steel washer 112 and lead slug 114 are so located that upon threadedly engaging the stop assembly 16 at the lower threaded end 22 of cutter housing 18, the steel washer H2 is in a fixed abutting relationship with the bottom surface of cutter housing 18.

In operation, a chain link is placed into the work-receiving opening 34, as best seen in FIG. 2, and bears upon the concave supporting surfaces 42. A cloth towel, or equivalent. is then wrapped around the chain both to center the chain link and to muffle the noise of the cutter piston 23 impacting upon the chain link. After making sure that the charge 48 is in place and that cutter piston 23 is in proper position the striker guide 62 is manually raised and then slammed down to fire. The cutter piston 23 is driven forward due to the expanding gases and punches through the chain link. The cutout section is driven into the steel washer 112 while the excess forces will cause the steel washer 112 to bend and the lead slug 114 to be extruded into a thin section thereby absorbing the excess energy. The collision is relatively noiseless due to the extrusion of lead slug 1M.

It is to be particularly noted that due to the strategic positioning of the O-rings as described hereinbefore, all gases resulting from the ignition of the explosive charge are confined substantially within the cutter housing 18. This feature makes possible the virtually noiseless operation of the tool as well as making underwater operation feasible. Thus, it will be seen that a man can easily handle such a tool by reason of it's lightness and compact construction and can position a chain link within the device with a relative ease not to be found in prior art devices. In emergencies, it can even be used as a gun by removing the stop assembly and using the cutter piston as an effective projectile which can be fired considerable distances when there is nothing in the work-receiving opening ofthe cutter housing.

To reuse the tool, the stop assembly 16 is disengaged from the cutter housing assembly 12 and set screw 116 is then turned thereby ejecting the bent steel washer H2 and ex truded lead slug 114 from the stop 110, Appropriate new pieces are inserted in the stop and the stop assembly is then threadedly affixed back to the cutter housing assembly l2v Cartridge 48 is then replaced by separating the striker guide assembly 14 from the cutter housing assembly 12 and removing the spent cartridge. A new cartridge is inserted and the striker guide assembly is then reassembled to the cutter hous ing assembly. The cutter piston 23 is then repositioned in bore 26 adjacent cartridge 48 and the tool is ready for another firing.

Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. it is therefore to be understood that within the scope ofthe tippended claims the invention may be practiced otherwise than as specifically described herein.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

l. A tool for cutting chain links comprising an elongate housing including a cylindrical section havin an axial cavity therein comprising a plurality of bores of successively increasing diameter, externally threaded portions formed in the upper and lower extremities of said housing, a work-receiving opening composed of a pair of arcuate surfaces positioned in back-to-back relationship thereby defining a truncated tapered protrusion and supporting surfaces, and an O-ring contained within an annular groove located above said upper thrc adcd pnrtion;

a cutter piston slidably positioned within an intermediate one of said bores including an elongate cylindrical member having a circumferentially extending annular groove at the upper end thereof and O-ring positioned within said groove;

an explosive charge positioned within the smallest diameter one ofsaid bores;

shock absorbing means detachably fixed to said lower and explosive actuation means including a substantially cylindrical retainer having upper and lower internally threaded portions, said lower threaded retainer portion threadedly coupled with said housing upper threaded portion, an elongate firing pin having a sealing portion ineluding two circular discs integral with said elongate firing pin within which an O-ring is positioned, a threaded cylindrical member positioned within said upper threaded retainer portion for fixedly positioning said firing pin against said explosive charge, said cylindrical member further including an annular groove containing an O-ring therein, slidable striker means for imparting a shock to said firing pin to actuate said explosive charge for driving said cutter piston into said work-receiving opening, and a low density polyurethane disc positioned between said striker means and said firing pin.

l IF l 

1. A tool for cutting chain links comprising: an elongate housing including a cylindrical section having an axial cavity therein comprising a plurality of bores of successively increasing diameter, externally threaded portions formed in the upper and lower extremities of said housing, a work-receiving opening composed of a pair of arcuate surfaces positioned in back-to-back relationship thereby defining a truncated tapered protrusion and supporting surfaces, and an Oring contained within an annular groove located above said upper threaded portion; a cutter piston slidably positioned within an intermediate one of said bores including an elongate cylindrical member having a circumferentially extending annular groove at the upper end thereof and O-ring positioned within said groove; an explosive charge positioned within the smallest diameter one of said bores; shock absorbing means detachably fixed to said lower threaded portion substantially limiting the slidable movement of said cutter piston, said shock absorbing means including a plastically deformable member and an overlying deformable disc member, a threaded member for fixedly positioning said deformable members in abutting relationship with the largest diameter one of said bores, and an internally threaded cylindrically shaped stop member threadedly attached to said housing lower threaded portion and containing said deformable member and said threaded member; and explosive actuation means including a substantially cylindrical retainer having upper and lower internally threaded portions, said lower threaded retainer portion threadedly coupled with said housing upper threaded portion, an elongate firing pin having a sealing portion including two circular discs integral with said elongate firing pin within which an Oring is positioned, a threaded cylindrical member positioned within said upper threaded retainer portion for fixedly positioning said firing pin against said explosive charge, said cylindrical member further including an annular groove containing an O-ring therein, slidable striker means for imparting a shock to said firing pin to actuate said explosive charge for driving said cutter piston into said work-receiving opening, and a low density polyurethane disc positioned between said striker means and said firing pin. 